Spectroscopy is a well-known method for investigating and determining a chemical composition of a sample, whether in solid, liquid or gaseous form. A fine laser, typically a single mode laser operating at a single wavelength, is directed at the sample. A scattered signal is collected through an optical probe and analyzed in a high resolution spectrometer. However, high resolution spectrometers are large and expensive. In a typical spectroscopy device, the spectrometer accounts for more than 75% of the cost and a similar percentage of the size and weight of the device.
Typically, high resolution spectroscopes are large and expensive. It is an ongoing task to reduce the size and cost of spectroscopy by using arrays of detectors, either as complementary metal-oxide semiconductors (CMOS), charge-coupled devices (CCDs) or using no silicon materials.
However, there are still no low cost filter arrays, where each filter has a different center wavelength. Filters are typically manufactured by stacking alternating thin film coatings. The thickness and composition of the materials defines the filter spectrum characteristics. But, with standard manufacturing techniques, there is no way to make a cheap filter array having unique filters with different center wavelengths.